Polypyrrole Hybrid Nanocomposite Electrode Materials with Outstanding Specific Capacitance

This study investigates the processing condition of modified carbon nanotube sheets doped with polypyrrole (CNTs-PPy) for high-performance energy storage applications, focusing on the impact of processing temperatures. The hybrid nanocomposites were prepared by coating CNTs with PI. The composites were then processed at three different temperatures 90°C, 180°C, and 250°C to study the effects of thermal treatment on their electrochemical properties. After processing, the composites underwent electrodeposition with polypyrrole (PPy) to enhance their electrochemical performance. A comprehensive set of electrochemical tests, including cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD), was employed to assess the nanocomposites' specific capacitance, charge-discharge efficiency, and cycling stability. The results revealed that the composite processed at 90°C exhibited the highest specific capacitance, reaching up to 655.34 F/g at a scan rate of 5 mV/s. This composite also demonstrated excellent cycling stability, with only minimal capacitance loss over 10 cycles. The superior performance at 90°C is attributed to the optimal microstructural properties achieved at this temperature, including enhanced porosity, and effective PPy deposition, all of which contribute to improved ion transport and reduced internal resistance. In contrast, composites processed at higher temperatures (180°C and 250°C) exhibited significantly lower specific capacitance and reduced cycling stability. These findings suggest that higher temperatures may induce adverse structural changes, such as increased bulk resistance and reduced porosity, which negatively impact the electrochemical performance of the composites. The study underscores the importance of carefully controlling processing temperatures to improve the structural integrity and electrochemical functionality of PI/CNTs-PPy hybrid nanocomposites for advanced energy storage systems.